Preparation of carbon monoxide by reaction of carbon dioxide with finely divided carbon in a fused salt bath containing a dissolved catalyst



United States Patent 3,385,668 PREPARATION OF CARBON MONOXIDE BY RE- ACTION OF CARBON DIOXIDE WITH FINELY DIVIDED CARBON IN A FUSED SALT BATH CONTAINING A DISSOLVED CATALYST 3,385,668 Patented May 28, 1968 bath and to obtain reaction rates which are of practical importance for other reaction in which CO is formed; and recovering the resulting carbon monoxide as it is evolved from the fused salt bath.

The process of this invention can be operated as a batch 5 Calvin A. Schunemann, Gates Mills, Ohio, assignor to Process In Whlch a slngle Charge of CafbQn Part1Cles 1S Horizons Incorporated, a corporation of New Jersey utilized in a fused salt melt or it may be run as a con- NO g- Flled PIOV. 1966, 596,055 tinuous process by intermittently or continuously replen- 4 Clalmsishing the carbon particle content of the fused salt bath. The invention will be more completely understood by ref- 1 l 1 n 0 o ABS CT OF THE DI SCLOSURE 1O erence to the foilowmg data illustrating the carrying out The preparation of carbon monoxide by reaction of carof this invention on a small scale. bon dioxide with finely divided carbon. The reaction is A stainle steel tank 4" wide, 8" long, deep was carried out in a fused salt bath in which a catalyst for the filled to a depth of approximately 8" with sodium chloreacton is dissolved. ride. The tank and its contents were heated to melt the salt. The tank and is contents were covered with a roof on Thls, mventlon relates to the pr pa n of carbon which were mounted a drive motor and a 3 inch, three y feactlon 0f f dlOXlde finely bladed imarine type propeller shaped stirred. The shaft of Vlded carbon a Salt eflvlroflment and In the Presthe stirrer was hollow so that a gas could be introduced ence of a catalyst dlssolved 111 said fused f into the salt under the blades of the stirrer. The stirrer r0- In many chemical processes carbon monoxide is utllized tated so h h motion f the l was d d under Pedllclng agent and thereby Carbon the blades of the propeller and up along the two end sides From the standpoint f 1t is often f of the tank. Ports were provided in the roof for viewing sirable to convert the carbon dioxide to carbon monoxide th ti f th Surface f h lt for reuse P the P Experiments were made to determine the yield of carq 0b]ect of Present mvfintlon 15 to PmVlde f bon monoxide produced when carbon dioxide is sparged effluent and economlcal preparatlon of carbon monoxlde into the molten sodium chloride bath maintained at a from carbon droxlde. temperature of approximately 1800 F. and containing yi the Prestint Procfiss lllvolves h f l g free carbon in the form of crushed petroleum coke of ap- Pl'eheatmg of El 8 Whlch Consists P P Y 0f proximately 30 mesh in amounts up to 10% by weight. C The carbon dioxide was sparged into the molten salt and Providing fllsed Salt bath m Whlch finely dwlded carbon mixture at rates ranging from .2 to 2.0 liters per carbon is distributed throughout the h; :minute. The impeller speed was maintained at approxi- (3) introducing the preheated gas into the fused salt mately 450 bath Containing finely divided Solid Carbon Partlcles; This series of tests was run utilizing carbon either as a (4) dissolving a catalyst in said fused Salt bath in Order blanket covering the melt or as a reactant mixed into the to maintain said particles dispersed throughout said salt salt.

TABLE I 002111 Salt CO1 in Run Bath Carbon Flow Rate, Temp, Exit Gas Remarks Liter/Min. F. (Percent) 1 Covered with 10 mesh cl1a.rcoal. 1. 0 1, 900 32. 4 .5 1,900 25.0 .25 1,900 14.0

Charcoal cover plus 5% petro- 1.0 1,900 14.0 Coarse petroleum coke.

leum coke in bath. 5 No charcoal cover plus 10% petro- 1. 0 1, 800 52.1 Salt depth 5".

leum coke in bath. 6 Ng ctollrer, 10% petroleum coke in 1. 0 1,800 38. 1 Salt depth 8".

a 7 ..do .5 1,800 27. 9

.do 1.0 1,800 40.6 Duplicate otrun 6. 9 Charcoal cover plus 10% petro- 1.0 1,800 18.2 Added minus 10 mesh leurn coke in bath. charcoal cover. 10 .do .5 1,800 9.9 11.. 10% Wt. petroleum coke (fine). 1.0 1,850 19.3

1 1. 0 1,850 Nil Nitrogen spurge, added 10% minus 30 mesh petroleum coke. .5 1,850 2.1 .5 1,850 2.0 d 1.1 1,850 2. 5 16 2% in Bath, remainder 011 surface- 1.1 1, 850 2. 8 17...... 1% in Bath, remainder on surface- 2. 0 1, 850 11. 4 18 8% Petroleum coke in bath.. 1. 0 1,850 6 Added 22% NazCOa. 10.. do 2.0 1,850 .4 20.. 15% Petroleum coke in bat 2. 0 1, 850 .8 Leak reduced salt level to 4". 21.. 12% Petroleum coke in both. .25 1,850 Atlislitilg to make 83% a2 3. 22 do 1.0 1,850 2.6 ..do.. 1.0 1,850 2.2 24 .do 2. 0 1, 850 2. 4 25 10% Petroleum Coke in Bath.-.-. 1. 0 1,850 1. 0 Added 1% NazCOa 20 do 1. 0 1,850 1.1 Added 1% NaQCOs 27 do 1. 0 1,850 Nil NarCoa .9% after addition.

11% Petroleum Coke in Bath..." 1. 0 ,850 8 N21100: .7% 12.8% Petroleum Coke in Bath 1. 0 ,850 6 Na2COs .9% ..do 1.0 1,850 .7

7% Petroleum Coke in Bath 5 1,850 .8 Sparger is partly clogged with deposit. 32 8% Petroleum Coke in Bath .5 1,850 .4

In runs 1 through 11 and 21 through 24, the CO gas feed was introduced into the bath through the hollow impeller without any preheating. In the remaining runs, the gas was preheated to approximately 1800 F. before being introduced into the bath.

In runs 1 through 17, the salt in the melt consisted entirely of sodium chloride, and in runs 18 through 32, a small amount of sodium carbonate was present in the melt.

From the results obtained, it is readily apparent that in order to obtain a satisfactory conversion of CO to CO, it is necessary to preheat the CO gas and to provide a suflicient residence time in the melt for the gas. It will also be seen that by the use of a small, but effective, amount of sodium carbonate the reaction is pushed still further toward completion.

While not wishing to be bound by any specific theory, it is believed that the carbon dioxide plus carbon reaction is catalyzed by the presence of sodium carbonate dissolved in the melt and behaving chemically, perhaps in the manner proposed in an article in Industrial and Engineering Chemistry, vol. 23 p. 250 et seq. (1931) or in Johnson et 211. United States Patent 2,921,840. The effectiveness of the catalysts is much greater when the carbonate is in solution.

Whatever the explanation, the operating conditions preferred in the practice of this invention are as follows:

(1) Salt temperature 18001900 F.

(2) Feed gas temperature 1500-1800 F.

(3) Carbonate content of bath 0.25 to 2% by weight dissolved in the salt bath.

(4) Between 5% and 15% by weight of finely divided carbon dispersed throughout salt bath.

(5) Preferably, but optionally, the melt is covered by a layer of charcoal particles, between about /2 and 1" in depth.

It is to be particularly noted that the carbon monoxide which is obtained contains much lower amounts of carbon dioxide than carbon monoxide produced by many other known processes, contents of less than 1% CO being readily obtainable by the process of this invention.

Having now described the invention it is not intended that it be limited except as may be required by the ap- 5 pended claims.

1. In a process for converting the CO content of a gas consisting principally of CO into CO which comprises reacting said gas with finely divided carbon, the improvements which comprise carrying out the reaction in a fused salt melt containing dispersed finely divided carbon and a catalyst dissolved in said melt;

preheating the CO containing gas;

introducing the preheated gas into the melt below the surface of said melt, in order to provide a sufficient residence time for said gas in said melt, for said gas to react with finely divided carbon particles dispersed in said melt; and

recovering the carbon monoxide so produced.

2. The process of claim 1 wherein the catalyst is an alkali metal carbonate.

3. The process of claim 1 wherein the CO containing gas is preheated to about 1800 F.

4. The process of claim 1 wherein the salt bath is 25 mechanically agitated during the process.

References Cited UNITED STATES PATENTS 1,163,922 12/1915 Hillhouse.

1,592,860 7/1926 Leonarz.

FOREIGN PATENTS 573,355 3/1959 Canada. 733,111 7/1955 Great Britain.

OSCAR R. VERTIZ, Primary Examiner.

H. M. S. MILLER, Assistant Examiner. 

